+- Jellyfin Forum (https://forum.jellyfin.org)
+-- Forum: Support (https://forum.jellyfin.org/f-support)
+--- Forum: Troubleshooting (https://forum.jellyfin.org/f-troubleshooting)
+--- Thread: SOLVED: Multiple Transcoding Errors with VA-API/Vulkan (/t-solved-multiple-transcoding-errors-with-va-api-vulkan)
Multiple Transcoding Errors with VA-API/Vulkan - Overlay1610 - 2024-11-01
Hi,
Jellyfin Version 10.10.0, Ubuntu 24.04.1
Installed on Proxmox, LXC has GPU, according to https://jellyfin.org/docs/general/administration/hardware-acceleration/amd#verify-on-linux "all is well" and should be working.
Using Chrome i get a "Playback Error - Playback failed due to a fatal player error." Same file works with direct play on the same PC with the Jellyfin Media Player.
Trying to run the specific command in CLI get's
Code:
[AVHWDeviceContext @ 0x5d6523c103c0] Failed to get number of OpenCL platforms: -1001.
Device creation failed: -19.
Failed to set value 'opencl=ocl:0.0' for option 'init_hw_device': No such device
Error parsing global options: No such deviceWhich is expected, since i have no OpenCL installed. However, Jellyfin trying to use OpenCL is not expected, as according to the docs, AMD GPUs only need VA-API and MESA.
Code:
root@jellyfin:/usr/lib# /usr/lib/jellyfin-ffmpeg/ffmpeg -v debug -init_hw_device drm=dr:/dev/dri/renderD128 -init_hw_device vulkan@dr
ffmpeg version 7.0.2-Jellyfin Copyright (c) 2000-2024 the FFmpeg developers
built with gcc 11 (Ubuntu 11.4.0-1ubuntu1~22.04)
configuration: --prefix=/usr/lib/jellyfin-ffmpeg --target-os=linux --extra-version=Jellyfin --disable-doc --disable-ffplay --disable-ptx-compression --disable-static --disable-libxcb --disable-sdl2 --disable-xlib --enable-lto=auto --enable-gpl --enable-version3 --enable-shared --enable-gmp --enable-gnutls --enable-chromaprint --enable-opencl --enable-libdrm --enable-libxml2 --enable-libass --enable-libfreetype --enable-libfribidi --enable-libfontconfig --enable-libharfbuzz --enable-libbluray --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libopenmpt --enable-libdav1d --enable-libsvtav1 --enable-libwebp --enable-libvpx --enable-libx264 --enable-libx265 --enable-libzvbi --enable-libzimg --enable-libfdk-aac --arch=amd64 --enable-libshaderc --enable-libplacebo --enable-vulkan --enable-vaapi --enable-amf --enable-libvpl --enable-ffnvcodec --enable-cuda --enable-cuda-llvm --enable-cuvid --enable-nvdec --enable-nvenc
libavutil 59. 8.100 / 59. 8.100
libavcodec 61. 3.100 / 61. 3.100
libavformat 61. 1.100 / 61. 1.100
libavdevice 61. 1.100 / 61. 1.100
libavfilter 10. 1.100 / 10. 1.100
libswscale 8. 1.100 / 8. 1.100
libswresample 5. 1.100 / 5. 1.100
libpostproc 58. 1.100 / 58. 1.100
Splitting the commandline.
Reading option '-v' ... matched as option 'v' (set logging level) with argument 'debug'.
Reading option '-init_hw_device' ... matched as option 'init_hw_device' (initialise hardware device) with argument 'drm=dr:/dev/dri/renderD128'.
Reading option '-init_hw_device' ... matched as option 'init_hw_device' (initialise hardware device) with argument 'vulkan@dr'.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option v (set logging level) with argument debug.
Applying option init_hw_device (initialise hardware device) with argument drm=dr:/dev/dri/renderD128.
[AVHWDeviceContext @ 0x5588da7b3940] Opened DRM device /dev/dri/renderD128: driver amdgpu version 3.57.0.
Applying option init_hw_device (initialise hardware device) with argument vulkan@dr.
[AVHWDeviceContext @ 0x5588da7b3b80] Supported layers:
[AVHWDeviceContext @ 0x5588da7b3b80] VK_LAYER_MESA_device_select
Last message repeated 1 times
[AVHWDeviceContext @ 0x5588da7b3b80] VK_LAYER_MESA_overlay
Last message repeated 1 times
[AVHWDeviceContext @ 0x5588da7b3b80] VK_LAYER_INTEL_nullhw
[AVHWDeviceContext @ 0x5588da7b3b80] Using instance extension VK_KHR_portability_enumeration
[AVHWDeviceContext @ 0x5588da7b3b80] GPU listing:
[AVHWDeviceContext @ 0x5588da7b3b80] 0: AMD Radeon Graphics (RADV RENOIR) (integrated) (0x1638)
[AVHWDeviceContext @ 0x5588da7b3b80] 1: AMD Radeon Graphics (RADV RENOIR) (integrated) (0x1638)
[AVHWDeviceContext @ 0x5588da7b3b80] 2: llvmpipe (LLVM 17.0.6, 256 bits) (software) (0x0)
[AVHWDeviceContext @ 0x5588da7b3b80] Requested device: 0x1638
[AVHWDeviceContext @ 0x5588da7b3b80] Device 0 selected: AMD Radeon Graphics (RADV RENOIR) (integrated) (0x1638)
[AVHWDeviceContext @ 0x5588da7b3b80] Using device extension VK_KHR_push_descriptor
[AVHWDeviceContext @ 0x5588da7b3b80] Using device extension VK_EXT_descriptor_buffer
[AVHWDeviceContext @ 0x5588da7b3b80] Using device extension VK_EXT_physical_device_drm
[AVHWDeviceContext @ 0x5588da7b3b80] Using device extension VK_EXT_shader_atomic_float
[AVHWDeviceContext @ 0x5588da7b3b80] Using device extension VK_KHR_external_memory_fd
[AVHWDeviceContext @ 0x5588da7b3b80] Using device extension VK_EXT_external_memory_dma_buf
[AVHWDeviceContext @ 0x5588da7b3b80] Using device extension VK_EXT_image_drm_format_modifier
[AVHWDeviceContext @ 0x5588da7b3b80] Using device extension VK_KHR_external_semaphore_fd
[AVHWDeviceContext @ 0x5588da7b3b80] Using device extension VK_EXT_external_memory_host
[AVHWDeviceContext @ 0x5588da7b3b80] Queue families:
[AVHWDeviceContext @ 0x5588da7b3b80] 0: graphics compute transfer (queues: 1)
[AVHWDeviceContext @ 0x5588da7b3b80] 1: compute transfer (queues: 4)
[AVHWDeviceContext @ 0x5588da7b3b80] 2: sparse (queues: 1)
[AVHWDeviceContext @ 0x5588da7b3b80] Using device: AMD Radeon Graphics (RADV RENOIR)
[AVHWDeviceContext @ 0x5588da7b3b80] Alignments:
[AVHWDeviceContext @ 0x5588da7b3b80] optimalBufferCopyRowPitchAlignment: 1
[AVHWDeviceContext @ 0x5588da7b3b80] minMemoryMapAlignment: 4096
[AVHWDeviceContext @ 0x5588da7b3b80] nonCoherentAtomSize: 64
[AVHWDeviceContext @ 0x5588da7b3b80] minImportedHostPointerAlignment: 4096
[AVHWDeviceContext @ 0x5588da7b3b80] Using queue family 0 (queues: 1) for graphics
[AVHWDeviceContext @ 0x5588da7b3b80] Using queue family 1 (queues: 4) for compute transfers
Successfully parsed a group of options.
Universal media converter
usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...
Use -h to get full help or, even better, run 'man ffmpeg'Different File results in
Code:
[AVFilterGraph @ 0x57e8c164fa40] Error initializing filters
[vost#0:0/h264_vaapi @ 0x57e8c1431d40] Error initializing a simple filtergraph
Error opening output file /Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f0.m3u8.
Error opening output files: Generic error in an external librarywhen using the player, however, on CLI using the exact same command
Code:
root@jellyfin:~# /usr/lib/jellyfin-ffmpeg/ffmpeg -analyzeduration 200M -probesize 1G -f matroska -i file:"/Medien/Filme/American Pie Presents Beta House (2008)/American Pie Presents Beta House (2007) Bluray-2160p.mkv" -map_metadata -1 -map_chapters -1 -threads 0 -map 0:0 -map 0:1 -map -0:s -codec:v:0 h264_vaapi -rc_mode VBR -b:v 1116000 -maxrate 1116000 -bufsize 2232000 -profile:v:0 high -sei -a53_cc -force_key_frames:0 "expr:gte(t,n_forced*3)" -vf "setparams=color_primaries=bt709:color_trc=bt709:colorspace=bt709,scale=trunc(min(max(iw\,ih*a)\,1280)/2)*2:trunc(ow/a/2)*2,format=nv12,hwupload_vaapi" -codec:a:0 libfdk_aac -ac 2 -vbr:a 5 -af "volume=2" -copyts -avoid_negative_ts disabled -max_muxing_queue_size 2048 -f hls -max_delay 5000000 -hls_time 3 -hls_segment_type fmp4 -hls_fmp4_init_filename "6ae0f395865e853a93dc3d272d8359f0-1.mp4" -start_number 0 -hls_segment_filename "/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f0%d.mp4" -hls_playlist_type vod -hls_list_size 0 -y "/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f0.m3u8"
ffmpeg version 7.0.2-Jellyfin Copyright (c) 2000-2024 the FFmpeg developers
built with gcc 11 (Ubuntu 11.4.0-1ubuntu1~22.04)
configuration: --prefix=/usr/lib/jellyfin-ffmpeg --target-os=linux --extra-version=Jellyfin --disable-doc --disable-ffplay --disable-ptx-compression --disable-static --disable-libxcb --disable-sdl2 --disable-xlib --enable-lto=auto --enable-gpl --enable-version3 --enable-shared --enable-gmp --enable-gnutls --enable-chromaprint --enable-opencl --enable-libdrm --enable-libxml2 --enable-libass --enable-libfreetype --enable-libfribidi --enable-libfontconfig --enable-libharfbuzz --enable-libbluray --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libopenmpt --enable-libdav1d --enable-libsvtav1 --enable-libwebp --enable-libvpx --enable-libx264 --enable-libx265 --enable-libzvbi --enable-libzimg --enable-libfdk-aac --arch=amd64 --enable-libshaderc --enable-libplacebo --enable-vulkan --enable-vaapi --enable-amf --enable-libvpl --enable-ffnvcodec --enable-cuda --enable-cuda-llvm --enable-cuvid --enable-nvdec --enable-nvenc
libavutil 59. 8.100 / 59. 8.100
libavcodec 61. 3.100 / 61. 3.100
libavformat 61. 1.100 / 61. 1.100
libavdevice 61. 1.100 / 61. 1.100
libavfilter 10. 1.100 / 10. 1.100
libswscale 8. 1.100 / 8. 1.100
libswresample 5. 1.100 / 5. 1.100
libpostproc 58. 1.100 / 58. 1.100
Input #0, matroska,webm, from 'file:/Medien/Filme/American Pie Presents Beta House (2008)/American Pie Presents Beta House (2007) Bluray-2160p.mkv':
Metadata:
title :
encoder : libebml v1.4.4 + libmatroska v1.7.1
creation_time : 2024-09-06T11:21:36.000000Z
Duration: 01:28:18.54, start: 0.000000, bitrate: 8858 kb/s
Chapters:
Chapter #0:0: start 0.000000, end 601.893000
Metadata:
title : Chapter 01
Chapter #0:1: start 601.893000, end 1202.076000
Metadata:
title : Chapter 02
Chapter #0:2: start 1202.076000, end 1802.009000
Metadata:
title : Chapter 03
Chapter #0:3: start 1802.009000, end 2402.275000
Metadata:
title : Chapter 04
Chapter #0:4: start 2402.275000, end 3000.998000
Metadata:
title : Chapter 05
Chapter #0:5: start 3000.998000, end 3605.977000
Metadata:
title : Chapter 06
Chapter #0:6: start 3605.977000, end 4205.952000
Metadata:
title : Chapter 07
Chapter #0:7: start 4205.952000, end 4805.092000
Metadata:
title : Chapter 08
Chapter #0:8: start 4805.092000, end 4983.687000
Metadata:
title : Chapter 09
Chapter #0:9: start 4983.687000, end 5298.518000
Metadata:
title : Chapter 10
Stream #0:0(eng): Video: av1 (libdav1d) (Main), yuv420p10le(tv), 3840x2160, SAR 1:1 DAR 16:9, 23.98 fps, 23.98 tbr, 1k tbn
Metadata:
title :
Stream #0:1(eng): Audio: dts (dca) (DTS), 48000 Hz, 5.1(side), fltp, 1024 kb/s (default)
Metadata:
title :
Stream #0:2(eng): Subtitle: hdmv_pgs_subtitle (pgssub), 1920x1080
Metadata:
title :
Stream #0:3(por): Subtitle: subrip (srt) (default)
Metadata:
title : Portuguese (Iberian)
Stream mapping:
Stream #0:0 -> #0:0 (av1 (libdav1d) -> h264 (h264_vaapi))
Stream #0:1 -> #0:1 (dts (dca) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
[libfdk_aac @ 0x62c269693100] Note, the VBR setting is unsupported and only works with some parameter combinations
[h264_vaapi @ 0x62c265c9ce80] Driver does not support some wanted packed headers (wanted 0xd, found 0x1).
[hls @ 0x62c265cd48c0] Opening '/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f0-1.mp4' for writing
Output #0, hls, to '/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f0.m3u8':
Metadata:
encoder : Lavf61.1.100
Stream #0:0: Video: h264 (High), vaapi(tv, bt709, progressive), 1280x720 [SAR 1:1 DAR 16:9], q=2-31, 1116 kb/s, 23.98 fps, 24k tbn
Metadata:
encoder : Lavc61.3.100 h264_vaapi
Stream #0:1: Audio: aac, 48000 Hz, stereo, s16 (default)
Metadata:
encoder : Lavc61.3.100 libfdk_aac
[hls @ 0x62c265cd48c0] Opening '/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f00.mp4' for writing
[mp4 @ 0x75c7dc70c300] Packet duration: -8 / dts: 144392 is out of range
[hls @ 0x62c265cd48c0] Opening '/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f01.mp4' for writing
[mp4 @ 0x75c7dc70c300] Packet duration: -16 / dts: 288728 is out of range
[hls @ 0x62c265cd48c0] Opening '/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f02.mp4' for writing
[hls @ 0x62c265cd48c0] Opening '/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f03.mp4' for writing
[hls @ 0x62c265cd48c0] Opening '/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f04.mp4' for writing
[mp4 @ 0x75c7dc70c300] Packet duration: -16 / dts: 720888 is out of range
[hls @ 0x62c265cd48c0] Opening '/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f05.mp4' for writing
[mp4 @ 0x75c7dc70c300] Packet duration: -16 / dts: 865272 is out of range
[hls @ 0x62c265cd48c0] Opening '/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f06.mp4' for writing
[hls @ 0x62c265cd48c0] Opening '/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f07.mp4' for writing
[mp4 @ 0x75c7dc70c300] Packet duration: -16 / dts: 1154024 is out of range
[hls @ 0x62c265cd48c0] Opening '/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f08.mp4' for writing
[mp4 @ 0x75c7dc70c300] Packet duration: -16 / dts: 1297368 is out of range
[hls @ 0x62c265cd48c0] Opening '/Medien/jellyfin/transcodes/6ae0f395865e853a93dc3d272d8359f09.mp4' for writing
[out#0/hls @ 0x62c265cc3500] video:3730KiB audio:666KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: unknown
frame= 705 fps= 93 q=-0.0 Lsize=N/A time=00:00:26.81 bitrate=N/A speed=3.52x
Exiting normally, received signal 2.I can also force a different error, if i change the Bitrate and "force" Transcoding of a direct playing file. Original File has 3 Mbps/s bitrate, setting transcode to 1.5 Mbps/s results in this:
Code:
Device creation failed: -542398533.
[vist#0:0/h264 @ 0x65528be4c5c0] [dec:h264 @ 0x65528be2b880] No device available for decoder: device type vaapi needed for codec h264.
[vist#0:0/h264 @ 0x65528be4c5c0] [dec:h264 @ 0x65528be2b880] Hardware device setup failed for decoder: Generic error in an external library
[vost#0:0/h264_vaapi @ 0x65528be27500] Error initializing a simple filtergraph
Error opening output file /Medien/jellyfin/transcodes/c7b3a827713491b1e63bd54c4dbb4a62.m3u8.
Error opening output files: Generic error in an external libraryAny advice would be much appreciated, thanks!
Edit: Here are the outputs of the commands in the docs:
Code:
/usr/lib/jellyfin-ffmpeg/vainfo --display drm --device /dev/dri/renderD128
Trying display: drm
libva info: VA-API version 1.22.0
libva info: Trying to open /usr/lib/jellyfin-ffmpeg/lib/dri/radeonsi_drv_video.so
libva info: Found init function __vaDriverInit_1_22
libva info: va_openDriver() returns 0
vainfo: VA-API version: 1.22 (libva 2.22.0)
vainfo: Driver version: Mesa Gallium driver 24.0.9 for AMD Radeon Graphics (radeonsi, renoir, LLVM 15.0.7, DRM 3.57, 6.8.12-2-pve)
vainfo: Supported profile and entrypoints
VAProfileMPEG2Simple : VAEntrypointVLD
VAProfileMPEG2Main : VAEntrypointVLD
VAProfileVC1Simple : VAEntrypointVLD
VAProfileVC1Main : VAEntrypointVLD
VAProfileVC1Advanced : VAEntrypointVLD
VAProfileH264ConstrainedBaseline: VAEntrypointVLD
VAProfileH264ConstrainedBaseline: VAEntrypointEncSlice
VAProfileH264Main : VAEntrypointVLD
VAProfileH264Main : VAEntrypointEncSlice
VAProfileH264High : VAEntrypointVLD
VAProfileH264High : VAEntrypointEncSlice
VAProfileHEVCMain : VAEntrypointVLD
VAProfileHEVCMain : VAEntrypointEncSlice
VAProfileHEVCMain10 : VAEntrypointVLD
VAProfileHEVCMain10 : VAEntrypointEncSlice
VAProfileJPEGBaseline : VAEntrypointVLD
VAProfileVP9Profile0 : VAEntrypointVLD
VAProfileVP9Profile2 : VAEntrypointVLD
VAProfileNone : VAEntrypointVideoProcCode:
root@jellyfin:~# ls -l /dev/dri
total 0
drwxr-xr-x 2 root root 80 Oct 28 19:11 by-path
crw-rw---- 1 root video 226, 1 Oct 28 19:11 card1
crw-rw---- 1 root syslog 226, 128 Oct 28 19:11 renderD128RE: Multiple Transcoding Errors with VA-API/Vulkan - nyanmisaka - 2024-11-01
Please provide the complete ffmpeg log instead of snippets, it does not help in debugging.
Also please share a screenshot of the settings in Dashboard->Playback->Transcoding.
RE: Multiple Transcoding Errors with VA-API/Vulkan - TheDreadPirate - 2024-11-01
And also provide your hardware specs.
RE: Multiple Transcoding Errors with VA-API/Vulkan - Overlay1610 - 2024-11-05
(2024-11-01, 04:17 PM)nyanmisaka Wrote: Please provide the complete ffmpeg log instead of snippets, it does not help in debugging.
Also please share a screenshot of the settings in Dashboard->Playback->Transcoding.
I've attached them, hope it helps.
(2024-11-01, 04:37 PM)TheDreadPirate Wrote: And also provide your hardware specs.
Jellyfin is running in an Debian 12 LXC on a fully upgraded Proxmox.
RE: Multiple Transcoding Errors with VA-API/Vulkan - TheDreadPirate - 2024-11-05
Are the mesa drivers also installed on Proxmox? I believe with LXCs you need drivers on both the host OS and LXC OS.
RE: Multiple Transcoding Errors with VA-API/Vulkan - Overlay1610 - 2024-11-07
(2024-11-05, 11:53 PM)TheDreadPirate Wrote: Are the mesa drivers also installed on Proxmox? I believe with LXCs you need drivers on both the host OS and LXC OS.
Yes, they are.
Code:
root@pve:/etc/modprobe.d# vainfo
error: can't connect to X server!
libva info: VA-API version 1.17.0
libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/radeonsi_drv_video.so
libva info: Found init function __vaDriverInit_1_17
libva info: va_openDriver() returns 0
vainfo: VA-API version: 1.17 (libva 2.12.0)
vainfo: Driver version: Mesa Gallium driver 22.3.6 for AMD Radeon Graphics (renoir, LLVM 15.0.6, DRM 3.57, 6.8.12-2-pve)
vainfo: Supported profile and entrypoints
VAProfileMPEG2Simple : VAEntrypointVLD
VAProfileMPEG2Main : VAEntrypointVLD
VAProfileVC1Simple : VAEntrypointVLD
VAProfileVC1Main : VAEntrypointVLD
VAProfileVC1Advanced : VAEntrypointVLD
VAProfileH264ConstrainedBaseline: VAEntrypointVLD
VAProfileH264ConstrainedBaseline: VAEntrypointEncSlice
VAProfileH264Main : VAEntrypointVLD
VAProfileH264Main : VAEntrypointEncSlice
VAProfileH264High : VAEntrypointVLD
VAProfileH264High : VAEntrypointEncSlice
VAProfileHEVCMain : VAEntrypointVLD
VAProfileHEVCMain : VAEntrypointEncSlice
VAProfileHEVCMain10 : VAEntrypointVLD
VAProfileHEVCMain10 : VAEntrypointEncSlice
VAProfileJPEGBaseline : VAEntrypointVLD
VAProfileVP9Profile0 : VAEntrypointVLD
VAProfileVP9Profile2 : VAEntrypointVLD
VAProfileNone : VAEntrypointVideoProc
root@pve:/etc/modprobe.d#RE: Multiple Transcoding Errors with VA-API/Vulkan - nyanmisaka - 2024-11-07
I'm not familiar with LXC but the FFmpeg error indicates that the VAAPI device initialization failed, which is probably due to permission issues.
RE: Multiple Transcoding Errors with VA-API/Vulkan - Overlay1610 - 2024-11-08
I mean, the log says it failed, because instead of using Vulkan, Jellyfin is starting the command with OpenCL - which is not installed and according to all documentation not needed.
But i have no idea if there's a setting for that, apparently VA-API does imply it's going to use Vulkan...but it doesn't
RE: Multiple Transcoding Errors with VA-API/Vulkan - nyanmisaka - 2024-11-09
Jellyfin determines Vulkan availability based on the output of:
Code:
/usr/lib/jellyfin-ffmpeg/ffmpeg -v debug -init_hw_device drm=dr:/dev/dri/renderD128 -init_hw_device vulkan@drPlease restart the server and try again. You should be able to find these in the server startup log
Code:
VAAPI device /dev/dri/renderD128 supports Vulkan DRM modifier
VAAPI device /dev/dri/renderD128 supports Vulkan DRM interopRE: Multiple Transcoding Errors with VA-API/Vulkan - Overlay1610 - 2024-12-01
For those wondering and stumbling across the literal darkness that's the logs in combination with an LXC - i finally found the fix.
I don't know why this isn't more obvious, as the Ubuntu in LXC reported "full" GPU Acceleration - but the LXC never had actual access to the GPU.
My Jellyfin LXC is a bit older and was updated from Ubuntu 22 to 24. Simply put, the Groups changed...
This is the Comment from tteck (RIP...gone way too soon) that got me on the right track:
https://github.com/tteck/Proxmox/discussions/2850#discussioncomment-10552091
Full Hardware Transcoding is now working.